The influx of neutrophils into the lung is known to be a cause of the destruction of functional lung tissue and the harmful symptoms of RDS, BPD, chronic lung disease, pulmonary fibrosis, asthma and COPD. Neutrophil influx is the migration of neutrophils from the blood into tissue in response to any type of irritation or injury to the tissue. In RDS, BPD, chronic lung disease and/or pulmonary fibrosis, asthma and COPD total cell influx and neutrophil influx results in damage to and destruction of pulmonary tissue, ultimately causing functional lung tissue to be replaced with non-functioning fibrotic tissue. Thus, neutrophil influx is ultimately responsible for causing pulmonary fibrosis to the lungs, which lead to damaged lung tissue and possibly death.
When circulating neutrophils are activated by chemical and cytokine signals released by damaged or irritated tissue, for example, by IL-8 from the lungs, they adhere to the walls of blood vessels in the damaged tissue, following the chemical and cytokine signal to the source, and migrate through the vascular endothelia and into the damaged lung. Neutrophils release many powerful enzymes, such as myeloperoxidase (MPO), an enzyme that chemically damages and modifies all proteins in its local vicinity, usually inactivating them. MPO damages local lung tissue and proteins, as well as those of the infectious agents. Neutrophils also release powerful proteases, such as elastase, that indiscriminately degrade host and pathogen proteins alike. Thus, activated neutrophils that migrate into the lungs in response to some irritation of the respiratory tract release non-specific destructive enzymes that damage the host's respiratory tissues, as well as any infectious agents present. These, and other, powerful non-specific destructive mediators released by neutrophils damage all cell types and destroy lung tissue, including breaking down the bronchiolar and alveolar structure, resulting in decreased lung function and respiratory distress. Local vascular structure is also damaged, resulting in increased vascular permeability and leakage of serum proteins into the lung and tracheal fluid, further impairing function.
This non-speciflc neutrophil response results in greater damage to respiratory tissue than the original irritant or infectious agent. Patients that develop respiratory symptoms or respiratory distress as a result of an exposure to an irritant such as an allergen, air-borne particulate matter, chemicals, or infectious agents often experience the worst symptoms after the irritant or infectious agent is cleared from the respiratory tract. Neutrophils are substantially responsible for this over-reaction.
Neutrophil influx to the lungs is measured in patients by counting the number of neutral-staining white cells per unit volume in tracheal fluids (referred to as tracheal aspirate fluid or TAF). Tracheal fluids are continuous with bronchial fluids, alveolar fluids, and nasal and sinus fluids. Tracheal fluid composition is representative of pulmonary fluids in the lower respiratory tract, as well as the upper respiratory tract (nasal and sinus fluid).
Cytokines, like IL-6 and IL-8, are released by local epithelial cells, endothelial cells, and fibroblasts. The levels of cytokines, for example IL-6 and IL-8, are measured in lung fluids such as TAF and in plasma or serum. Cytokines are basic regulators of all neutrophil functions. Under normal conditions, neutrophils move along microvascular walls via low affinity interaction of selectins with specific endothelial carbohydrate ligands. However, during the inflammatory response, chemotactic factors and proinflammatory cytokines signal the recruitment of neutrophils (neutrophil influx) to sites of infection and/or injury. Neutrophils then penetrate the endothelial layer and migrate through connective tissue to sites of injury, for example the lungs, where they accumulate and adhere to extracellular matrix components such as fibronectin and/or collagen.
RDS affects 10% of all premature infants and only rarely affects those born at full-term. RDS also affects adults. The disease is caused by a lack of lung surfactant, a chemical that normally appears in mature lungs, or by tissue damage to the lungs from being on a mechanical ventilator and oxygen for a significant amount of time. Surfactant keeps the air sacs from collapsing and allows them to inflate with air more easily. In respiratory distress syndrome, the air sacs collapse and prevent the child from breathing properly. In infants, symptoms usually appear shortly after birth and become progressively more severe. If symptoms of RDS persist, the condition is considered BPD if a baby is dependent on artificially supplied oxygen at 36 weeks' postconceptional age (PCA—also known as post-conceptual age). In a child or adult, if symptoms of RDS persist, the condition is considered chronic lung disease and/or pulmonary fibrosis if the patient is dependent on artificially supplied oxygen following a respiratory distress episode.
BPD affects 20-60% of all premature, very low birth weight infants. BPD and RDS are associated with substantial morbidity and mortality as well as extremely high health care costs. Although the widespread use of intratracheally administered exogenous surfactant and antenatal steroid therapy has reduced the overall severity of BPD, the prevalence of this condition has increased with improved survival of very low birth weight infants, BPD is a multi-factorial disease process that is the end result of an immature, surfactant deficient lung that has been exposed to hyperoxia, mechanical ventilation and infection. Furthermore, it is well documented that increased concentrations of cytokines and cells present in the tracheal aspirate fluid of premature infants within the first few days of life are associated with the subsequent development of RDS and BPD. Still further it is known that higher levels of fibronectin are present in the tracheal fluid and lungs of patients suffering from RDS and BPD and thus it causes and contributes to respiratory distress. Thus, treating and preventing RDS and BPD by providing improved lung function during the first few days of life of a premature infant is critical to the long term survivability of the infant.
Asthma is a chronic lung condition characterized by difficulty in breathing. Symptoms include: wheezing, coughing shortness of breath and chest tightness. People with asthma have extra sensitive or hyperresponsive airways. The airways react by narrowing or obstructing when they become irritated. This makes it difficult for the air to move in and out. This narrowing or obstruction causes the symptoms of asthma. The narrowing or obstruction of the airways is caused by: airway inflammation (meaning that the airways in the lungs become red, swollen and narrow) or bronchoconstriction (meaning that the muscles that encircle the airways tighten or go into spasm)
COPD is a lung disease in which the lungs are damaged, making it hard to breathe. In COPD, the airways are partly obstructed, making it difficult to get air in and out of the lungs. Most cases of chronic obstructive pulmonary disease (COPD) develop after repeatedly breathing in fumes and other things that irritate and damage the lungs and airways, for example by smoking. The lungs and airways are highly sensitive to irritants. They cause the airways to become inflamed and narrowed, and they destroy the elastic fibers that allow the lung to stretch and then return to its resting shape. This makes breathing air in and out of the lungs more difficult. COPD may also be caused by a gene-related disorder called alpha 1 antitrypsin deficiency. Alpha 1 antitrypsin is a protein that inactivates destructive proteins. People with antitrypsin deficiency have low levels of alpha 1 antitrypsin; the resulting imbalance of proteins leads to the destruction of the lungs and COPD.
Symptoms common to RDS, BPD, chronic lung disease, pulmonary fibrosis, asthma and COPD include respiratory insufficiency (i.e. lungs unable to adequately oxygenate the blood and remove carbon dioxide), increased airway resistance, inflammation and fibrosis of the lungs. Each of these symptoms are substantially caused by excessive levels of neutrophils, IL-6, IL-8, and total cells in the tracheal fluid. Excess total protein in the tracheal aspirate fluid (“TAF”) or bronchoalveolar lavage fluid (“BAL”) is also associated with lung inflammation and fibrosis in MDS, BPD, chronic lung disease, pulmonary fibrosis, asthma and COPD.
Glucocorticoids, also known as corticosteroids, are powerful anti-inflammatory agents that are known to improved lung function, to reduce the incidence of BPD in premature infants, and to improve the symptoms of RDS, BPD, chronic lung disease and/or pulmonary fibrosis, asthma and COPD. However, they are not completely safe to use. There are dangerous, often life-threatening side effects associated with the use of glucocorticoids in infants, children and adults. In infants, corticosteroids are avoided in clinical practice because they cause growth retardation, disproportionate growth inhibition of the central nervous system and head, and severe neurological impairment. In children, normal growth is stunted, resulting in small stature, due to treatment with corticosteroids. And in adults, cardiovascular complications, including hypertension and stroke, are major side effects of corticosteroids. In all patients, corticosteroids lower the patient's immune function and leave them susceptible to infection of all types (bacterial, viral, fungal, etc.), sometimes resulting in a lethal infection. Thus, safety is a major consideration in the choice of anti-inflammatory agent used to treat, prevent or cure RDS, BPD, chronic lung disease and/or pulmonary fibrosis, asthma and COPD and their related respiratory symptoms, reduce the severity of asthma or allergy, and prevent the progression of existing chronic lung disease such as COPD or the development of chronic lung disease such as BPD. It is a significant challenge to find an anti-inflammatory agent powerful enough to alleviate respiratory symptoms and which is safe to use.
Human CC10 (hereinafter CC10), also known as uteroglobin, is a small homodimeric secretory protein produced by mucosal epithelial cells. In humans, Clara cells, a type of mucosal epithelial cell located in the airways, are the main site of CC10 production. CC10 also circulates in the blood and is excreted in urine. CC10 is known to have anti-inflammatory properties. CC10 inhibits secretory PLA2, an enzyme that degrades surfactant and facilitates eicosanoid biosynthesis. Eicosanoids are a family of lipdphilic compounds including prostaglandins, leukotrienes, thromboxanes, and other arachidonic acid metabolites.
Further information concerning rhCC10, its structure and methods of use is found in U.S. Pat. No. 6,255,281, its continuation-in-part, U.S. patent application Ser. No. 09/087,210, and in the following U.S. Patent Application Publication Nos.: US 2002-0160948, US 2002-0160948, US 2003-0008816, US 2003-0109429, US 2003-0207795, US 2002-0173460, US 2002-0169108, US 2005-0261180, US 2004-0047857, and US 2006-0025348, all of which are incorporated by reference in their entirety.
Very low concentrations of CC10 have been found in the TAF or BAL of patients suffering from RDS, Asthma and COPD and BPD. For example, very low concentrations of CC10 have been found in the tracheal aspirate fluid (TAF) of ventilated premature infants suffering from BPD relative to normal levels. These infants are not yet able to produce enough natural CC10 on their own, and develop severe lung inflammation. Normally, the appearance of CC10 in the amniotic fluid dates from 16 weeks of gestation and increases as a function of gestational as well as postnatal age. CC10 concentrations in tracheal fluid, measured by determining the amount of CC10 protein in the tracheal aspirate fluid, of premature infants born at 28-32 weeks of gestation have been found to be 2-4 orders of magnitude less than those found in the tracheal sputum (a.k.a. tracheal fluid) of healthy adults. CC10 concentrations correlate in a negative fashion with the concentration of inspired oxygen required by preterm infants with BPD. That is, infants with lower CC10 in TAF require greater amounts of supplemental oxygen. In fact, not only are CC10 concentrations lower in tracheal fluid from infants who either died or developed BPD, but the limited amount of available CC10 was oxidized and demonstrated less immunoreactivity relative to controls.
Recombinant CC10 (recombinant human CC10) has not been previously used to treat patients, including preterm infants for a number of reasons. First, rhCC10 of sufficient purity has not been previously available. Nor was it known whether rhCC10 caused specific toxicity or triggered an immune response to endogenous CC10 when administered. Furthermore, CC10 is known to inhibit platelet aggregation, thus negatively impacting the ability of the blood to clot. CC10 is also known to suppress the immune system, which could lead to adverse patient consequences, render recipients more susceptible to infection, and prohibit its use in humans, including premature infants. It was not known what dosage or dosage range would avoid deleterious immunogenicity, specific toxicity, and inhibition of platelet aggregation and suppression of the immune system.
Furthermore, it was not known whether rhCC10 would cause significantly lower total protein concentrations in the tracheal fluids of patients or what dosage to administer to achieve significantly lower total protein concentrations in the tracheal fluid of patients, a necessary outcome in treating BPD.
Additionally, it was not known whether rhCC10 would cause significantly lower total cell, neutrophil, IL-6 or IL-8 levels in patients or which dosage to administer to achieve significantly lower neutrophil, IL-6 or IL-8 levels in patients, also a necessary outcome in treating RDS, BDP, chronic lung disease and/or pulmonary fibrosis, Asthma, and COPD.
As shown below, the prior technological difficulties in using CC10 to provide a safe, well-tolerated and effective treatment for RDS, BDP, chronic lung disease, pulmonary fibrosis, asthma, and COPD have been overcome.